The present invention relates to a keyboard device and a method of controlling a power supply internally incorporated in the keyboard device. More particularly, the present invention relates to a keyboard device which is connected in operation to an external device such as a communication terminal including a personal computer, a portable telephone or the like, and to a method of controlling the power supply of the keyboard device.
With the increase in the number of users who performs communications or exchange data by means of an electronic mail via a portable or cellular telephone as a communication terminal, the users increasingly encounter occasions to enter characters and letters via the telephone. When a conventional cellular phone is used to enter characters, successive key operations are required for the user, imposing a troublesome burden on the user.
To support or facilitate operability of the cellular phone, an external keyboard device is known which is connected via a cable to a cellular phone or the like, to receive the power from that phone. The keyboard device of this type does not incorporate its own power supply. Likewise, as for the keyboard device used to connect to a personal computer, operating power is supplied from the computer itself.
In the conventional keyboard device of the personal computer or the cellular phone, once the power switch provided in the keyboard device is turned on, then the power supplied from the personal computer or cellular phone is dissipated by the device.
This may in some cases cause a problem that, when the user tries to send a message or mail to the designated destination after entering desired characters via the keyboard device, the power in the power supply required to send the electronic mail has become insufficient.
To overcome the drawbacks, there has been proposed a keyboard device which incorporates its own power supply, from which the device operates. This power supply is completely independent of the power supply used to operate the personal computer or the cellular phone. In the keyboard device, the power required when the user enters characters is supplied from the power supply incorporated in the device itself The keyboard device is usually connected to the personal computer or the cellular phone, only when a message is sent via the electronic mail. In this case, the power supply equipped in the personal computer or the cellular phone is the source of power used when entering characters.
As for a keyboard device of another type, one which is used by directly inserting a part of the cellular phone into the keyboard device, is also known as a keyboard device of slot-in type.
However, the above-mentioned keyboard devices relating to the prior art internally incorporate their own power supply, therefore, when the power switch provided in the devices is turned on, the devices dissipate the power, regardless of whether or not the devices are connected to the personal computer or the cellular phone. This disadvantageously reduces the operable time of the keyboard device.
When the conventional keyboard device is put in a bag or the like, under a condition of being connected to the personal computer or the cellular phone, the power to the personal computer or the cellular phone is undesirably turned on in some cases. To prevent such a trouble, a hard box is provided to reside the keyboard device. In some cases, to prevent undesired operation of the keyboard device or the like which will occur when a particular key on the keyboard device is kept depressed, a cover unit is provided to protect the keys.
The present invention has been made considering the above-mentioned problems. It is an object of the present invention to provide a keyboard device capable of controlling efficiently its own internal power supply. It is an another object of the present invention to provide a method of controlling the power supply internally incorporated in the keyboard device, for allowing to reduce the power dissipation in the device.
In accordance with the present invention, there is provided a keyboard device which is internally incorporating a power supply, said device comprising: a first monitor means for monitoring a connection state of said keyboard device with respect to an external device; and a control means for controlling a state of said power supply in accordance with said connection state obtained by said first monitor means.
It is preferable that said control means performs control to set said keyboard device to an active state, if said first monitor means monitors to determine a connection between said keyboard device and said external device.
It is preferable that said control means performs control to set said keyboard device to a standby state, if said first monitor means fails to determine a connection between said keyboard device and said external device.
It is also preferable that the present invention further comprises a second monitor means for monitoring a key operation, wherein said control means performs control to set said keyboard device to a standby state, if said second monitor means determines that there is no key operation for more than a predetermined period of time.
Preferably, said control means performs control to set said keyboard device to a standby state, if said second monitor means determines that any key is kept depressed for more than a predetermined period of time.
Preferably, said external device is a communication terminal.
In accordance with another aspect of the present invention, there is provided a method of controlling a power supply internally incorporated in a keyboard device, comprising: a first monitoring step of monitoring a connection state of said keyboard device with respect to an external device; and a step of controlling a state of said power supply in accordance with said connection state obtained in said first monitoring step.
It is preferable that the method of controlling a power supply according to the present invention, said keyboard device is so controlled in said controlling step that the device is set to an active state, if it is determined in said first monitoring step that a connection has been made between said keyboard device and said external device.
It is also preferable that the method of the present invention, said keyboard device is so controlled in said controlling step that the device is set to a standby state, if it is determined in said first monitoring step that no connection has been made between said keyboard device and said external device.
It is also preferable that the method according to the present invention further comprises a second monitoring step of monitoring a key operation, wherein in said controlling step, said keyboard device is so controlled that the device is set to a standby state, if it is determined in said second monitoring step that there is no key operation for more than a predetermined period of time.
In accordance with the present invention method, said keyboard device is so controlled in said controlling step that the device is set to a standby state, if it is determined in said second monitoring step that any key has been kept depressed for more than a predetermined period of time.
Preferably, in the method according to the present invention, said external device is a communication terminal.